1. Field of the Invention
The present invention relates to speech recognition, and more specifically to natural language speech recognition. Even more specifically, the present invention relates to a natural language speech recognition system used to control an application.
2. Discussion of the Related Art
Many have dreamed of a device that could completely bridge the gap or seam between man-made machines and humans. Speech recognition techniques have been used to enable machines to recognize human speech. For example, speech recognition technology is used in many applications, such as word processing, control of devices, and menu driven data entry.
Most users prefer to provide the input speech in the form of a natural language. Natural language is written or spoken input that is in natural form such as if the user is actually conversing with the machine. In contrast, non-natural language is limited in syntax and structure. To communicate with the machine in non-natural language, the user must know and speak commands or requests according to the syntactic and semantic structure of the speech recognition engine.
Advantageously, a natural language interface system permits the user to easily interface with the machine or system, since the user can simply speak in a conversational manner without having to remember the proper format to speak a command or request. Disadvantageously, natural language interface systems are difficult to implement due to the complex and shifting “rules” of human natural language.
Furthermore, natural language processing of the prior art has been inefficient and rigid in its ability to recognize the meaning of natural language utterances. As such, in order to limit the context of the user's natural language input and ease the processing of the input speech, conventional natural language interface systems are dialog-based or prompt-driven. The natural language interface controls the context of the speech being input to the system. For example, natural language interfaces have been implemented as automated phone systems, such as an automated natural language airline reservation system. Such systems prompt the user to speak within a certain context. For example, the natural language system asks the user what city would the user like to fly. As such, the system dictates to the user the context of the speech it expects. Thus, the natural language interface system will look for natural language indicating names of cities. Next, the system will prompt the user to speak what date the user would like to fly. Again, the context of the response is dictated by the natural language interface system. Disadvantageously, the user is unable to provide open-ended information or an open ended request. If the received speech data is not within the context as prompted by the system, the system will either ignore the request, inform the user that the response is not understood or potentially misinterpret the request as falling within the context of the prompt.
What is needed is an efficient natural language system in which the context is not limited by the natural language processing, but is limited by the user's speech. The present invention advantageously addresses the above and other needs.